A team of investigation led by UCL (University College London) has created the ‘nanopasta’: the thinnest spaghetti in the world, about 200 times thinner than a human hair.
Although made from flour, these spaghetti are not intended to be a new food, but were created because of the wide uses that the extremely thin strands of material, called nanofibers, have in medicine and industry.
Nanofibers made from starch, produced by most green plants to store excess glucose, are especially promising and could be used in bandages to aid wound healing (since nanofiber mats are very porous, allowing the entry of water and humidity, but keeps bacteria out), as a scaffold for bone regeneration and for the administration of medications. However, they depend on starch being extracted from plant cells and purified, a process that requires a lot of energy and water.
A more environmentally friendly method, the researchers say in a statement, is to create nanofibers directly from a starchy ingredient like flour, which is the base of pasta.
In a new paper in Nanoscale Advances, the team describes making spaghetti just 372 nanometers (billionths of a meter) in diameter using a technique called electrospinning, in which threads of flour and liquid are pulled through the tip of a needle. through an electric charge. The work was carried out by Beatrice Britton, who carried out the study as part of her master’s degree in chemistry at UCL.
Co-author Dr Adam Clancy said: “To make spaghetti, a mixture of water and flour is passed through metal holes. In our study, we did the same thing, except we passed our flour mixture through them with an electrical charge. They are literally spaghetti but much smaller.”
The thinnest known pasta is a thousand times thicker
In their paper, the researchers describe the next finest known pasta, called su filindeu (“threads of God”), handmade by a pasta maker in the town of Nuoro, Sardinia. This pasta lunga (“long pasta”) is estimated to be about 400 microns wide, 1,000 times thicker than the new electrospun creation, which, at 372 nanometers, is narrower than a few wavelengths of light.
The novel “nanopaste” formed a mat of nanofibers about 2 cm in diameter, so it is visible, but each individual strand is too narrow to be clearly captured by any type of visible light camera or microscope, so its widths were measured with a scanning electron microscope.
Co-author Professor Gareth Williams said: “Nanofibres, such as those made from starch, show potential for use in wound dressings as they are highly porous. Additionally, nanofibers are being explored for use as a scaffold to regenerate tissue, as they mimic the extracellular matrix, a network of proteins and other molecules that cells build to maintain themselves.”
Dr Clancy said: “Starch is a promising material to use as it is abundant and renewable (it is the second largest source of biomass on Earth, behind cellulose) and is biodegradable, meaning it can be break down in the body.
“But purifying starch requires a lot of processing. We have shown that a simpler way to make nanofibers using flour is possible. The next step would be to investigate the properties of this product. “We want to know, for example, how quickly it disintegrates, how it interacts with cells and whether it can be produced on a large scale.”
Professor Williams added: “Unfortunately, I don’t think it would be useful as a pasta as it would overcook in less than a second, before you can remove it from the pan.”
In electrospinning, the needle containing the mixture and the metal plate on which the mixture is deposited form the two ends of a battery. By applying an electrical charge, the mixture completes the circuit by exiting the needle onto the metal plate.
Electrospinning with a starchy ingredient, such as white flour, is more complicated than with pure starch, since the impurities (proteins and cellulose) make the mixture more viscous and unable to form fibers.
The researchers used flour and formic acid instead of water, since formic acid breaks down the giant stacks of spirals (or helices) that make up the starch. This is because the layers of helices glued together are too large to be the building blocks of nanofibers. (Cooking has the same effect on starch as formic acid: it breaks down the layers of helices, making the pasta digestible.)
The formic acid evaporates as the noodles fly through the air to the metal plate.
The researchers also had to carefully heat the mixture for several hours before slowly cooling it again to ensure it was the right consistency.